LG CU500 - Cell Phone, Service Manual

Page: 38 / 186

3. TECHNICAL BRIEF
- 39 -
3.8.5 Serial Bus Interface(SBI)
The MSM6275 device’s SBI is designed specifically to be a quick, low pin count control protocol for
QUALCOMM’s RTR6250, RFR6202, RFL6202, and PM6650 ASICs. Using the SBI, the RTR6250,
RFR6202, RFL6202, and PM6650 devices can be configured for different operating modes and for
minimum power consumption, extending battery life in Standby mode. The SBI also controls DC
baseband offset errors.
3.8.6 Wideband CODEC
The MSM6275 device integrates a wideband voice/audio CODEC into the mobile station modem
(MSM). The CODEC supports two differential microphone inputs, one differential earphone output, one
single-ended earphone output, and a differential analog auxiliary interface. The CODEC integrates the
microphone and earphone amplifiers into the MSM6250 device, reducing the external component
count to just a few passive components. The microphone (Tx) audio path consists of a two-stage
amplifier with the gain of the second stage set externally. The Rx/Tx paths are designed to meet the
ITU-G.712 requirements for digital transmission systems.
3.8.7 Vocoder Subsystem
The MSM6275 device’s QDSP4000 supports AMR,FR,EFR and HR. In addition, the QDSP4000 has
modules to support the following audio functions: DTMF tone generation, DTMF tone detection, Tx/Rx
volume controls, Tx/Rx automatic gain control (AGC), Rx Automatic Volume Control (AVC), EarSeal
Echo Canceller (ESEC), Acoustic Echo Canceller (AEC), Noise Suppression (NS), and programmable,
13-tap, Type-I, FIR, Tx/Rx compensation filters. The MSM6275 device’s integrated ARM9TDMI
processor downloads the firmware into the QDSP4000 and configures QDSP4000 to support the
desired functionality.
3.8.8 ARM Microprocessor subsystem
The MSM6275 device uses an embedded ARM926EJ-S microprocessor. This microprocessor,
through the system software, controls most of the functionality for the MSM device, including control of
the external peripherals such as the keypad, LCD, RAM, ROM, and EEPROM devices. Through a
generic serial bus interface (SBI) the ARM926EJ-S configures and controls the functionality of the
RFL6202, RFR6202, RTR6250, RTR6200, and PM6650 devices.
3.8.9 Mode Select and JTAG Interfaces
The mode pins to the MSM6275 device determine the overall operating mode of the ASIC. The options
under the control of the mode inputs are Native mode, which is the normal subscriber unit operation,
ETM mode, which enables the built-in trace mode, and test mode for factory testing. The MSM6275
device meets the intent of the ANSI/IEEE 1149.1A-1993 feature list. The JTAG interface can be used
to test digital interconnects between devices within the mobile station during manufacture.